Unless I'm very much mistaken, the Rainmaker was played by veteran character actor Royal Dano, whose credits include Gunsmoke, The Outlaw Josey Wales, The Right Stuff and Twin Peaks.

Rainmakers,
travelling showmen who claimed to be able to hold drought at bay, had
their heyday in the early 20th century and re-emerged during the
dust-bowl era of the 1930s. One of the most notorious, Charles Hatfield
(right), was the inspiration for the 1956 film The Rainmaker, starring Burt Lancaster.